Decorative thermosetting laminates are well-known and used for instance as covering material for walls, cupboard doors, desktops tabletops, for other furniture and as flooring material.
Such laminates are often made of two to seven craft paper sheets impregnated with phenol-formaldehyde resin, a monochromatic or patterned decor paper sheet impregnated with melamine-formaldehyde resin and a fine so-called overlay sheet of .alpha.-cellulose impregnated with melamine - formaldehyde resin.
The overlay sheet is intended to protect the decor paper sheet from abrasion. In certain cases the overlay sheet is omitted.
There are also laminates consisting of a base layer of particle board or fibre board provided with such a decor paper sheet and possibly an overlay sheet. These sheets can be laminated towards the base layer under heat and pressure. If a decor paper sheet only is used and no overlay sheet, the decor paper sheet can be glued towards the base layer instead.
The laminates have many good properties. However, it has turned out that there is a great need of improving the abrasion resistance of the laminates exposed to an extreme abrasion. This is especially the case with laminates for floors but to a certain extent also laminates for desktops and tabletops.
It has been tried before to improve the abrasion resistance of these laminates by addition of small, hard particles for instance of aluminum oxide already at the production of the overlay paper of .alpha.-cellulose. Then the particles have been spread over a layer of wet .alpha.-cellulose fibers on the wire of a paper machine.
With this method, the particles are distributed more or less irregularily within the whole fibre layer. Some of these particles even pass through the wire. Thus, in the overlayer paper obtained the hard particles will be distributed in an uncontrollable way. It is impossible by this known method to get an even distribution of the hard particles on the surface of the paper, where they give the best effect against abrasion.
In other words, the laminates obtained containing such an overlay sheet will get an uneven quality regarding abrasion resistance.